Color photographic light-sensitive materials which are now widespread fall into two main groups, i.e., color photographic light-sensitive materials for picture taking such as color negative film, color reversal film and color instant film and color photographic light-sensitive materials for printing the recorded image for observation such as color paper, reversal paper and display film. Among these color photographic light-sensitive materials for picture taking, positive type photographic light-sensitive martials such as color reversal film and instant film are double-purpose photographic light-sensitive materials which can be put into use for picture taking as well as observation. Photographic light-sensitive materials only for picture taking cannot make the picture taken observable without any corresponding printing materials. Thus, these photographic light-sensitive materials for picture taking essentially need the subsequent use of such printing materials. For the foregoing double-purpose photographic light-sensitive materials as well, printing materials (duplicating materials) are required in the case where it is desired to prevent the original from being damaged, e.g., in the case where it is stored as a valuable original or processed as a printing original, or in the case where an enlarged duplicate or a plurality of duplicates are needed.
These printing materials can be roughly divided into two groups. Typical examples of these printing materials include color reversal paper or color auto positive paper which makes the printed image observable on reflected light from a reflective support and color duplicating film or display film which makes the printed image observable by means of transmitted light or projected image through a transparent or translucent support. Among these printing materials, the color duplicating film can make the printed image observable by means of transmitted light simultaneously with its original positioned side by side and thus requires quite the same image quality as the original. The color duplicating film is further practically required to provide an image faithfully duplicating the original. That is, the color duplicating film is required to serve as a printing original or a stock photograph which is subject to prolonged storage. However, it is actually very difficult to reproduce quite the same image quality as the original due to the problems of the properties of photographic light-sensitive materials, the performance of printers, the printing technique, etc.
The quality of color images is mainly determined by three factors, i.e., gradation reproducibility, color reproducibility and image quality reproducibility (granulairy and sharpness). Among these factors, gradation reproducibility is a factor particularly important to color duplicating film which is desired to provide faithful reproduction.
Heretofore, for tone reproducibility, attempts have been made to provide faithful reproduction without impairing the tone of the original. It is desired to provide faithful reproduction of an original comprising objects ranging from a highlight such as white cloud to a shadow such as dark hair of a person standing in the shade. However, this can be not so easily accomplished. In order to provide better tone reproduction of the original, attempts have been made to make the characteristic curve of photographic light-sensitive materials desirable.
An approach as disclosed in JP-A-61-50135, JP-A-63-128337, JP-A-63-91658, JP-A-63-202739 and JP-A-64-10244 (The term "JP-A" as used herein means an "unexamined published Japanese patent application") is an example of the foregoing attempts. These approaches are intended to meet the foregoing requirements by defining the point gamma value (first order differential value) in a certain density range on the characteristic curve to a predetermined range. However, these approaches are intended mainly for reflective materials and thus are not suitable for transparent materials which provide a color transparency directly through a transparency, to which the present invention is intended to be applied. In particular, these approaches are quite insufficient for color duplicating film, which is often subjected to contact exposure process for image formation.
It has thus been desired to develop a technique for enabling faithful reproduction of tone and color inherent to the original without any problems.